Method of and apparatus for drilling wells



s L L E w G N I L L L M am ZO mw Aw Hm .A Lw .A WD N A. F OA D O H ml E M A 2 9 A.. 1 .L C 0 Filed May 31, 1918 5 sheets-sheer 1 INVENTOR v fifa/fer /v/afze WITNESSES:

ATTORNEY Oct. 14. 1924. 1,511,990

w. L. HARTZELI.

METHOD OF AND APPARATUS FOR DRILLING WELLS Filed May .'51, 1918 3 Sheets-Sheet. 2

AUX/L/AY MOTO/ MAIN MUTUI? 7 o /5 72 H. R renoue 7,' /5

REM $PEED` /5 HP ToRoL/E 75 ffy 7 WITNESSES: INVENTOR Oct. 14 1924. 1,511,990 A w` 1 HARTzELL.

METHOD OF AND APPARATUS FOR DRILLING WELLS Filed May- 5l, 1918 3 Sheets-Sheet. 5

AUX/UAI? Y MOTOR MA/N. M0 70H WITNESSES: l W iENOR im, /MMV C W d Z@ Pafented oct. 14, 1924.

UNITED STATES PATENT OFFICE.

WALTER L. HARTZELL, F WILKINSBURG, PENNSYLVANIA, ASSIGNOB TO WmTmG- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 0F PENNSYL- VANIA.

METHOD AND APPARATUS FOR DRILLING WELLS.

Application led May 31, 1918. Serial No. 237,566.

To all 'whom it may concern:

Be it known that I, WALTER L. HARTznLL,

a citizen of the United States, and a res".-

dent of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Methods of and Apparatus for Drilling Vells, of which the following is a specification, v

My invention relates to a method of and apparatus for electrically drilling oil wells, and particularly to an electrical means of cable drilling in which a drilling tool or bit is fastened to a cable suspended from awalking beam that is rocked or operated by electric motive power.

The power requirements of the different drilling operations vary.l through a wide range. The power required for operating the drilling tool is more or less continuous..

while .that required for handling the casing of thewell and for hailing is very intermittent.

The tool on the end of the cable is alternately lifted and dropped by the walking beam, and to obtain etliciency in the drilling operation,` when the tool is dropped, the power or dr-five must automatically speed up so that when the tool strikes the drilling blow and rebounds the cable will catch the tool and lift it on .the 11p-stroke before it starts to fall back again.

' This cycle is continued as the drilling progresses but, in order to be able to drill rapidly and prevent excessive wear and breaking of the drilling cable, with each depth of well and with different weights l of tools and with different formations to be drilled through, the speed of the motor 40 mustfbe variable to give the best working g speed, and the speed must increase rapidly when the tool is dropped and this pick up speed must be adjustable with increasing depths so that the cab-le will be ready to pick the tool up on the rebound after it has struck the drilling blow. Furthermore, the driving power must be of sutilcient capacity to handle .the casing for the well and other neces/sary operations. 50` 'Heretofore, a single comparatively large slip-ring, variable-speed, alternating-current electric motor of from 50. to 75 horsepower capacity has been used for all purposes. Smaller motors have been used but generally have proven too small to handle the casing satisfactorily. While only from 15 to 30 horsepower is needed for the actual drilling, the extra capacity is required to 'handle the steel casing which is from 12 to 24 inches in diameter and so heavy that a string of it weighs tons. Since the actual drilling involves about 90% of thc total operations, there is a considerable waste of power when such a large motor is used and, inasmuch as the motor carries only about one-fourth load, it gives a poor power factor and low eiliciency, which makes the cost of power high. The con trol of the speed of the large drilling motor is effected by the use of a 9-point main controller and an auxiliary controller connected in series with the main controller, whereby a rough and a fine speed adjustment may be obtained during the drilling operation. Since there is but a small load on the motor, the range of .the possible speeds is very limited, and the pick up of the motor to synchronous Saeed will be slow on account of the large inertia of its rotor. These limitations and defects of the single large electric drilling motor render it impossible to obtain and maiutain the proper motion of the bit and the same therefore often operates dead,

that is, it does not always strike the proper drilling blow as it rebounds dead. Furthermore, a lsingle large motor is very uneconcmical because of the increased cost of power due to the low power factor and low efficiency, and the slow rate of drilling makes the interest, labor cost and overhead expenses high. Delay in reaching the pay sand allows vthe adjacent lease holder to obtain so much more oil, if he has operating wells, which, of course, is an indirect loss to the drilling producer. When the well is finished, the large motor, not being suitable for pumping, involves a loss in dead capital tied up in the motor and its controlling devices.

The object of my invention is therefore to provide a method and apparatus for electrically drilling oil wells that will practically eliminate the above mentioned undesirable Jfeatures encountered in the use of a single. large electric motor. To this end, l employ two or more substantially similar electric motors having their shafts n'xechanically connected together, and controlled by individual controllers, as hereinafter more fully explained.

rl`he above and other objects and the novel features of my invention will be apparent from the following description taken in connection with the drawing in which Figure 1 is a side elevational view ot' an oil well drilling apparatus embodying my invention; Fig. 2 is a plan view of the same: Pigs. 3, -l and 5 are views illustrating other ways of mechanically connecting the two electric motors; Fig. 6 is a group ot' speed-torque curves of two small electric motors mechanically connected together, showing the same as used and controlled according to the method and apparatus embodying my invention; F ig. 7 is a group of speed-torque curves of a single large electric motor, as heretofore employed for drilling purposes; and Fig. 8 is a group-of speed-torque curves ol the double-rated mechanically connected smaller motors. cach developing 15 horsepower at (300 R. P. M. and 30 horsepower at 1200 Pi. P. ll/l.

Referring to Figures 1 and 2 of the drawing, two or more substantially similar alternating current wound-rotor electric motors 10 and 11 have their rotor shafts mechanially connected together by some suitable means as a common shaft coupling, belt or chain. The pulley 12, carried by a shaft mechanically connecting the two motors and driven thereby, is connected to the pulley 13 on the countershaft 14 hy a belt 15,- the countershaft being belted to the band wheel 16 that drives the shaft 17 carrying a crank 18 connected to one end of the walking beam 19 that is pivoted at 20. The arrangement in Figures 1 and 2, whereby the motors 10 and 11 may be mechanically connected so that both motors can apply their power to the same load, may be varied. Figures 3, 4. and 5 illustrate three other ways ot' accomplishing the same purpose and still other ways may be adopted. ln Figure 3, the motors 10 and 11 are belted to the same band wheel 131 on the shaft 14.. In Fig. 4, the motors 10 and 11 are belted by separate belts to similar band wheels 132 and 133 both fast on the countershatt 14. In Fig. 5, the two motorsl() and 11 are connected by a single belt to the band wheel 134. the belt passing around an idler pulley I. The outer end of the walking beam has a drilling tool or bit 21 suspended therefrom by the cable 22 that unwinds from the cable drum 23 as the bit descends and the depth of the well increases. In! order to raise the tool and cable, the drum 23 may be driven from the band wheel 17 by a rope 24. The motors are'la Lariano preferably wound so as to normally rotate in opposite directions, so that, when the pnlley ends of the armature shafts are mechanically connected together, the two armatures will rotate in the same direction.

The motors 10 and 11 are preferably each of smaller capacity than the large electric motor heretofore employed, beingapproximately 15 and 30 horsepower, GOO-120() R. P. M. double-rated two speed typgJ or 15 and 45 horsepower star-delta, 900 R. M. single speed type. Each motor is equipped with a double-throw switch S for changing the connections of the windings, so as to give a low rating and a high rating, or t0 change the number of poles and change the synchronous speed of the motors. For example, the full load power developed by the two speed type motors may be 15 H. P. at 600 R. P. M., 30 H. P. at 600 R. P. lll., 30 H. P. at 120() R. P. M. or 60 H. P. at 1200 R. P. M., or by the 15 and 15 horsepower star-delta single speed, 15 horsepower at 900 R. P. M., 30 horsepower at 900 R. P. M., 45 horsepower at 900 R. P. M., 90 horsepower at 900 R. l). M. Since the motors may be operated at any one of these full load ratings, a higher etiiciency and a higher power factor are obtainable. which reduces the power expense and the line loss and voltage fluctuations in the transmission system.

The controlling mechanism for the mechanically connected motors 10 and 11 consists of two reversing controllers, 101, 111` one for each motor, adapted to give 50 100 per cent speed' control in nine steps, more or less. These controllers vary the resistances 102, 112. in the secondary circuits ot the motors independently of each other and, as the motors are connected together me- 105 chanically, a variation of the resistance of either motor (1) will cause the load to be shifted from one motor to the other, (2) will change the average speed, and (3) will also change the relative speed when the 110 load is on and when it is ofi'. By varying the combination ot' resistances, the operator can regulate the number of strokes per minute, simultaneously with the proper ratio of the up stroke to the down stroke 115 and thereby obtain the most eflicicnt drilling motion. The very wide range of speeds obtainable by the use of two motors and two independent controllers permits the operator to closely approximate the correct drill- 120 ing motion as the depth of the wel] increases. This prevents the tool from drilling dead and renders possible a. more rapid drilling, lessening the time required to reach the pay sand. reducing the'labor 125 cost and the interest charges on non-producing investments.r and enabling the operator to obtain much oil that he would .otherwise not get on account of slow drill- The feeder circuits that connect the motors 10 and 11 to the three-phase line a, b, c, include the line switches or circuit breakers 25 and 26, respectively, to protect the motors and to disconnect the apparatus from the power line at will. Ammeters 27 and 28 or other suitable electrical measuring meters Vare connected to series transformers 271 and 281, respectively. and are located in the derrick D within sight of the operator to indicate to him what proportion of the load each motor is taking. Levers 29 and 30. connected by cables 291 and 301 to the drums of the controllers 101 and 111, respectively, are also located at the operators position in the derrick. A maximum torque relay (not shown) may also be connected to the high rated side of each motor and arranged to insert resistance in the secondary circuit thereof so each motor will give a maximum torque at zero speed.

.Since the motors 10 and 1l are each nearer the capacity required for drilling operations, they may be operated at approximately full load instead of less than onequarter load, as in the case of the single larger motor, and, therefore, the maximum range of speed control may be obtained on each motor during the drilling operation. From the curves of Fig. 7, it will be seen that-,a horsepower drilling motor operating under a load of about 15 to 20 horsepower and controlled b-y a main controller and auxiliary controller connected in series gives a limited range of operating speeds and a very limited range of pick-up speeds. For example, the pick-up speed for point l, indicated by that part of curve m between l and X or synchronous speed, is but slightlygreater comparatively than the pick-up speed for point 9 of the controller, which is indicated by that part of curve n between 9. and X. rlhe pick-up speeds for the intermediate points of the controller are between points l and 9 and, of course, the range of pick-up speeds is thus quite limited. With the use of the auxiliary controller, operating speeds may be obtained between those corresponding to the steps of the main controller but the range is'necessarily limited by the main controller.

Assuming that power is applied to one motor only, the other motor running idle, and the torque required to lift the tool is equal to the 15 horsepower or the 'full load torque of one motor, then 9 different speeds can be obtained corresponding to the 9 points of the controller for the 'main motor, as indicated by the points I, II, III, IV, V, VI, VII, VIII, IX on the curves at the right of line OX in Fig. 6. In each case, when the tool is dropped, the speed will laccelerate to the point..

Again, assuming the same torque condi-w tion but with power applied to both motors and the controllers for each motor operated on the same relative controller point, then each motor will take one-half of the total load or develop a torque corresponding to 71/2 horsepower and a further 9 different speeds will be obtained, as indicated on Fig. by the points a, b, c, d, e, f, g, L and 9. In each case, when the tool is dro ped, the Speed will accelerate to the point but with a different acceleration period than with the power only driving the one main motor. Although some of the speeds obtained are approximately the same, the rate of acceleration to the point X is different.

By using different points on the auxiliary controller from those on the main controller, a large number of different speeds can be obtained, as indicated by the points on the curves between the 71/2 horsepower and 15 horsepower lines, and in each case with a different acceleration rate to the point X when the tool is dropped.

The particular combination I have shown and described gives a total of 54 points with a considerable range of both speed and acceleration rate, using the same size motors and 9-point controllers and similar resistances. These results can all be modified by (l) using different size motors, (2) using controllers having more or less controller points, (3) using more controller points on one controller than on the other and (4) using resistances of different capacities.

However, for simplicity and commercial reasons, it is more desirable to use motors and controllers of the same size. The resistance connections can easily be varied if any particular results are desired or, if necessary to get lower control steps, more resistance can be added to the auxiliary motor with very little trouble and expense.

The inherent accelerating capacity of the two Small motors is greater than that of the single large motor, since their diameters arc approximately one-half that of the larger motor and their combined weight is about the same, the fly wheel effect or inertia which varies as WR2 is about one-fourth that of the large motor. For this reason, the acceleration of the main and auxiliary motor will be much quicker than the single large motor when the tool is dropped, which, in conjunction with the greater speed range and the adjustment of the pick-up speed make this apparatus and method especially suitable for drilling at va-ryin depths, with different weights of tools and t rough different formations.

Referrin to Fig. 6, since the to quired to lift the tool is constant an ue reequal to OM or the torque at l5 horsepower, both the speed and the proportion of the load carried by either motor can be obtained from the curves for any setting of the main and auxiliary controllers by simply finding the points where the distance between the curves corresponding to the main controller and the curve corresponding to the auxiliary controller is equal tov OM. This is shown on the drawing b lines A-B-C,`for two combinations. A represents the load on the main motor and'BC the load on the auxiliary motor. In each 'case AB-l-BCzOM, or the total torque requiredk to lift the drilling tool.

The pull-out torque or maximum torque of each motor is represented by OL and OL', or a total torque equal to L'L can be exerted by the two motors.

The curves of Figure 8 represent the double rating obtained when throwing the switches on the 15/30-600/1200 R. P. M. motor. The curve FXF' is the same as shown in Fig. 6. The curve GXG is the curve on the ninth point, or with resistance all out and the motors operating on the high rating side. The curve HXH shows the operation when the amount of resistance is out into the secondary on the high side to ive maximum torque at zero speed which 1s automatically obtained on the high rating side of the motor when a maximum torque relay is used. The maximum toqIl-e or prulling power of the two motors is When using the 15/45 horsepower star-delta connected motor, similar curves are obtained except the speed is not changed.

With either the double-rated two-speed motor or the double-rated star-delta connected motor, the maximum torque or pullout torque on the high rating side is from three to four times full load torque so that with the two motors a torque equal or greater than that of the large single motor is obtained and also the .same speed control is obtained on the high rating side as on the low rating side, givino' great ilexibility and quick operation. lso, in operations like hailing sand which require less power than handling casings, one motor can be used instead of two and thus again adapt the motor capacity to the work at hand giving better eflicieney and power factor andreducing power consumption;

The equipment used for drilling can be used without any change or additional expense for pumping two separate wells.

From the foregoing, it will be seen that, by the use of a driving means consisting of two independently controlled but mechan cally connected electric motors, I am able to do all of the work heretofore accomplished by the use of a single large motor, and, in addition, numerous advantages are obtainable `that are not possible with the single large motor. A greater range of speeds and rates of acceleration are obtainable, and greater rapidity and economy in operation are possible. While I have shown and described the method and apparatus in detail, it will be understood that numerous modifications may be made therein without departing from the spirit and Scope. of the invention.

What l claim is:

l. The method of drilling wells that comprises operating the drilling tool by means ot a plurality of mechanically connected electric motors, and controllin the division of load on said motors indepen ently to vary the total driving capacity of said plurality of mechanically -connected motors over a relatively wide range.

2. The method of drilling wells that comprises operating the drilling tool b a plurality of mechanically connectedY electric motors, and-controlling the load carried by said motors independently to permit of a relatively wide range of speed at small increments.

3. The method of drilling wells that comprises operating the drilling tool by power derived from two electric motors havi mechanically connected rotors, and electrically controlling said motors independently o ermit of a wide range of speeds and oa s.

4. The method of drilling wells that comprises operating the drilling tool by power derived from two alternating current elecf tric motors having mechanically connected rctors, and electricall controlling each motor independently o the other, whereby a large range of resultant driving speeds are obtained for operating the drilling tool.

5. The method of drilling wells that comprises operating the drilling 'tool by power derived from two electric motors having the rotors thereof mechanically connected together, and controlling each motor independently of the other, whereby the total driving capacity of the combination 0f the mechanically connected rotors may be vay ried.

6. The method of drilling wells that comprises operating the drilling tool by power derived from two alternating current electric motors having rotors mechanically connected ,to lthe same driven member, and resistances in circuit with the windings of said rotors, and varying the resistance in one rotor circuit independently of the resistance in the other rotor circuit to permit of a wide range in speed at small increments. i

7 The method of drilling wells that comprises operating the drilling tool by means of a plurality of mechanically connected motors and controlling said motors independently to vary the division of power between them whereby the driving speed thereof is varied over a rela/tively wider range than is obtained by a single moltor.

8. The method of drilling wells that comprises operating the drilling tool by means betweenv 'them-y whereby Sthcg-driving :"speed,

thereof isjfvar-ied 'over a- Vrelatively wider range thany is obtainable by a single electric motor-ofthe.capacityz'ogf lsaidp uralityof motors. y y v v 9. Thecombination with well yd.rilling apy reciprocating paratus having a vertiv tool or bit,4 of', 'operating means for reity of mechanically connected induction.

motors,I andt means for 'controlling' such motors independently of one; another toobtainf awide frange of resultant speeds in a comparatively drreat number of ste whereby the irate. joi acceleration or pick-up ,speedv of such operating means synchronizes with such 'drilling tool during substantially` its entire loperation and under the val rions drilling conditions encountered.

10. The'combination'with a well drilling apparatus, 'of means for operating the same comprisingv two mechanically' connected doubleratedzelectric motors, and controllers ...for independently varying the output and speed' of said motors whereby the motors develop low tor ue low speed for drilling and high torque igh speed for other operations.

11. The combination with power transmitting means, of a plurality of alternatingy current electric motors arranged for severally and jointly supplyin power to said means, and means trolling said electric motors to vary the speed and division of thereby.

12. In a power plant for drilling wells, the combination with a walking beam, a drilling 4tool operatively connected to one end and a band Wheel operatively connected to the other end, of two electric motors for driving the band wheel, and means for so dividing the load between the motors as to obtain a wide range of speed in the band wheel.l y

13. In a power plant for drilling wells, the. combination with a walking beam, a drilling tool operatively connected to `one end anda bandwheel operatively connected to the other end, of two alternating current electricmotors having wound secondaries for driving the band wheel, and means for independently varying the resistance of said power developed or in ependently con.

ling the speed torque characteristics of said motors during the joint operation thereof f bymeans of varying the secondary currents thereof.

".15. In a well drilling device, the combinal `gtion with av drilling tool and two induction ciprocalting fsaidftool.I comprising' av plural.l

tion with two induction motors for actuat ing the drilling tool, of means for so controlling the ratio of the speeds of the motors on the down or loaded stroke and the up stroke as to synchronize with the time period-of the drilling tool.

17. In a well drilling device, the combination with a drilling tool and a casing, of two operatively connected motors, and means for so independentl controlling the motors that they may be changed from low torque low speed operating meansv for the tool to high speed high torque handling means for the casing.

18. Well drilling apparatus comprising a drilling tool and 'means for operating the same comprising two mechanically `connected induction motors having wound-seconda` ries and means for independently varying the resistances of said secondaries to change the speed-torque characteristics of said operating means.

19. In an oil-well drilling system, the combination with a drilling tool and electric driving means therefor, of means for periodically accelerating the driving means at the'top of the drill stroke.

20. In an oil-well drilling system, the combination with a drilling tool and electric driving means therefor, of means for periodically accelerating the driving means at the top of the drill stroke and for periodically slowing down the driving means at the bottom ot' the drill stroke.

In testimony whereof, I have hereunto subscribed my name this 23rd day of May,A 

